黔南山地烤烟合理群体结构的光合机制研究

Photosynthetic Mechanism of Reasonable Population Structure ofFlue-Cured Tobacco in Southern Guizhou Mountainous Area

为研究不同群体结构下烤烟的光合响应机制,本试验采用裂区设计,以行距为主区(R1:100 cm;R2:110 cm),种植密度为副区(D1:15000株·hm^(-2);D2:18000株·hm^(-2);D3:21000株·hm^(-2)),探究黔南山地适宜的烤烟群体结构。结果表明,R2行距较R1显著提高了烤烟群体叶面积指数(LAI),群体LAI随种植密度增加先增加后降低。中部叶向值随行距和密度增加而显著增大,下部叶则呈相反变化趋势;R2D2、R2D3处理上、中部与R1D2、R2D1处理下部的叶向值显著高于其他处理。R2行距较R1显著增加了中、下部叶透光率,上、中部叶透光率随密度增加而显著降低,R2D1处理中部叶的透光率显著高于其他处理,R1D3的中、下部叶透光率显著低于其他处理。D3下部叶的SPAD值显著高于D1;R2D3上部叶的SPAD值与R1D2差异不显著,显著高于其他四个处理,R2D3下部叶的SPAD值显著高于R2D2、R1D1。行距增加提高了光化学猝灭系数(qP),降低了非光化学猝灭系数(NPQ);密度增加降低了烤烟的实际量子产量[Y(Ⅱ)]、电子传递速率(ETR)和qP。R2D1的qP显著高于R1D2、R1D3和R2D3,R1D2的NPQ显著高于R1D3和R2D2。烤烟单株干物质积累量与上等烟比例随种植密度的增加呈先增加后降低趋势,而群体干物质积累量与产量则随种植密度的增加而提高。综上,在黔南山地植烟生态区,110 cm的行距和18000株·hm^(-2)的种植密度有利于合理群体结构的建成和干物质积累量的提高。本研究结果为黔南山地烤烟的优质适产提供了技术参考。

This experiment utilized a split-plot design with row spacing as the main plots(R1:100 cm,R2:110 cm)and planting density as the sub-plots(D1:15000 plants·hm^(-2),D2:18000 plants·hm^(-2),D3:21000 plants·hm^(-2))to investigate the photosynthetic response mechanism of flue-cured tobacco under different population structures,and to explore the most appropriate flue-cured tobacco population structure for the mountainous region of southern Guizhou.The findings demonstrated that the leaf area index(LAI)of the flue-cured tobacco population was significantly higher with R2 row spacing when compared to R1,and the population’s LAI increased initially before decreasing as density increased.The leaf orientation value of the middle leaf significantly increases with the increase in row spacing and density,whereas the lower leaf shows an opposite trend.The leaf orientation values of the upper and middle R2D2 and R2D3 treatments and the lower R1D2 and R2D1 treatments were significantly higher than those of other treatments.When compared to R1,the middle and lower leaves’light transmittance was greatly improved by R2 row spacing,while the upper and middle leaves’light transmittance decreased significantly as density increased.In the R2D1 treatment,the middle leaves’light transmittance was considerably greater than those in the other treatments.In contrast,in the R1D3 treatment,the middle and lower leaves’light transmittance were significantly lower than those in the other treatments.The SPAD value of lower leaf D3 was significantly higher than that of D1.R2D3 in the bottom leaves had a substantially higher SPAD value than R2D2 and R1D1,and the value of R2D3 in the upper leaves was not substantially different from R1D2,but was significantly higher than those of other four treatments.The photochemical quenching coefficient(qP)rises with increasing row spacing,while the non-photochemical quenching coefficient(NPQ)decreases.The actual quantum yield[Y(Ⅱ)],electron transfer rate(ETR),and qP of flue-cured tobacco are all considerably reduced with density.The qP of R2D1 was significantly higher than those of R1D2,R1D3 and R2D3,and the NPQ of R1D2 was significantly higher than those of R1D3 and R2D2.While the dry matter accumulation and yield of the group grew with the increase in planting density,the proportion of dry matter accumulation and top-grade tobacco in a single plant of roasted tobacco initially increased before decreasing.In general,in the tobacco planting ecological plot of southern Guizhou Mountain,the 110 cm row spacing and planting density of 18000 plants·hm^(-2)favor the development of an acceptable population structure and the enhancement of dry matter accumulation,which provides a technical reference for the high-quality and suitable yield of flue-cured tobacco in southern Guizhou Mountain.